1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
|
/* $OpenBSD: rthread_fork.c,v 1.9 2013/06/25 22:51:46 guenther Exp $ */
/*
* Copyright (c) 2008 Kurt Miller <kurt@openbsd.org>
* Copyright (c) 2008 Philip Guenther <guenther@gmail.com>
* Copyright (c) 2003 Daniel Eischen <deischen@freebsd.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD: /repoman/r/ncvs/src/lib/libc_r/uthread/uthread_atfork.c,v 1.1 2004/12/10 03:36:45 grog Exp $
*/
#if defined(__ELF__)
#include <sys/types.h>
#include <sys/exec_elf.h>
#pragma weak _DYNAMIC
#endif
#include <errno.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include "thread_private.h" /* in libc/include */
#include "rthread.h"
struct rthread_atfork {
TAILQ_ENTRY(rthread_atfork) next;
void (*prepare)(void);
void (*parent)(void);
void (*child)(void);
};
static TAILQ_HEAD(atfork_listhead, rthread_atfork) _atfork_list =
TAILQ_HEAD_INITIALIZER(_atfork_list);
static struct _spinlock _atfork_lock = _SPINLOCK_UNLOCKED;
pid_t _thread_sys_fork(void);
pid_t _thread_sys_vfork(void);
pid_t _dofork(int);
pid_t
_dofork(int is_vfork)
{
pthread_t me;
pid_t (*sys_fork)(void);
pid_t newid;
#if defined(__ELF__)
sigset_t nmask, omask;
#endif
sys_fork = is_vfork ? &_thread_sys_vfork : &_thread_sys_fork;
if (!_threads_ready)
return sys_fork();
me = pthread_self();
/*
* Protect important libc/ld.so critical areas across the fork call.
* dlclose() will grab the atexit lock via __cxa_finalize() so lock
* the dl_lock first. malloc()/free() can grab the arc4 lock so lock
* malloc_lock first. Finally lock the bind_lock last so that any lazy
* binding in the other locking functions can succeed.
*/
#if defined(__ELF__)
if (_DYNAMIC)
_rthread_dl_lock(0);
#endif
_thread_atexit_lock();
_thread_malloc_lock();
_thread_arc4_lock();
#if defined(__ELF__)
if (_DYNAMIC) {
sigfillset(&nmask);
_thread_sys_sigprocmask(SIG_BLOCK, &nmask, &omask);
_rthread_bind_lock(0);
}
#endif
newid = sys_fork();
#if defined(__ELF__)
if (_DYNAMIC) {
_rthread_bind_lock(1);
_thread_sys_sigprocmask(SIG_SETMASK, &omask, NULL);
}
#endif
_thread_arc4_unlock();
_thread_malloc_unlock();
_thread_atexit_unlock();
#if defined(__ELF__)
if (_DYNAMIC)
_rthread_dl_lock(1);
#endif
if (newid == 0) {
/* update this thread's structure */
me->tid = getthrid();
me->donesem.lock = _SPINLOCK_UNLOCKED_ASSIGN;
me->flags &= ~THREAD_DETACHED;
me->flags_lock = _SPINLOCK_UNLOCKED_ASSIGN;
/* this thread is the initial thread for the new process */
_initial_thread = *me;
/* reinit the thread list */
LIST_INIT(&_thread_list);
LIST_INSERT_HEAD(&_thread_list, &_initial_thread, threads);
_thread_lock = _SPINLOCK_UNLOCKED_ASSIGN;
/* single threaded now */
__isthreaded = 0;
}
return newid;
}
pid_t
fork(void)
{
struct rthread_atfork *p;
pid_t newid;
_spinlock(&_atfork_lock);
TAILQ_FOREACH_REVERSE(p, &_atfork_list, atfork_listhead, next)
if (p->prepare)
p->prepare();
newid = _dofork(0);
if (newid == 0) {
TAILQ_FOREACH(p, &_atfork_list, next)
if (p->child)
p->child();
} else {
TAILQ_FOREACH(p, &_atfork_list, next)
if (p->parent)
p->parent();
}
_spinunlock(&_atfork_lock);
return newid;
}
pid_t
vfork(void)
{
return _dofork(1);
}
int
pthread_atfork(void (*prepare)(void), void (*parent)(void),
void (*child)(void))
{
struct rthread_atfork *af;
if ((af = malloc(sizeof *af)) == NULL)
return (ENOMEM);
af->prepare = prepare;
af->parent = parent;
af->child = child;
_spinlock(&_atfork_lock);
TAILQ_INSERT_TAIL(&_atfork_list, af, next);
_spinunlock(&_atfork_lock);
return (0);
}
|
